49 C.F.R. § 821.52 : Transportation — OTHER REGULATIONS RELATING TO TRANSPORTATION — NATIONAL TRANSPORTATION SAFETY BOARD — RULES OF PRACTICE IN AIR SAFETY PROCEEDINGS — SPECIAL RULES APPLICABLE TO PROCEEDINGS INVOLVING EMERGENCY AND OTHER IMMEDIATELY EFFECTIVE ORDERS — General

(a) Applicability. This subpart shall apply to any order issued by the Administrator under 49 U.S.C. 44709 as an emergency order, as an order not designated as an emergency order but later amended to be an emergency order, and any order designated as immediately effective or effective immediately.
(b) Effective date of emergency. The procedure set forth herein shall apply as of the date on which written advice of the emergency character of the Administrator's order is received and docketed by the Board.
(c) Computation of time. Time shall be computed in accordance with the provisions of §821.10.
(d) Waiver. Except as provided in § 821.54 (f), or where the law judge or the Board determines that it would unduly burden another party or the Board, a certificate holder (respondent) affected by an emergency or other immediately effective order of the Administrator may, at any time after filing an appeal from such an order, waive the applicability of the accelerated time limits of this subpart; however, such a waiver shall not serve to lengthen any period of time for doing an act prescribed by this subpart which expired before the date on which the waiver was made.
(e) Acceptable methods of filing and service. All documents submitted by a party in a proceeding governed by this subpart must be filed with the Board by overnight delivery, facsimile or electronic mail, and simultaneously served on all other parties by the same means. If filing by electronic mail, parties must adhere to the requirements in § 821.7 (a)(3).

49 C.F.R. § 821.52

68 FR 22625, 4/29/2003, as amended at 77 FR 63252, 10/16/2012